Method of inhibiting foaming in steam boilers



Patented Oct. 31, 1950 UNITED PM OFFICE METHOD "or INHIBITING FOAMING IN STEAM BOILERS Lewis 0. Gunderson, Park Ridge, 111., assignor to Dearhorn. Chemical Company, Chicago, 111., a corporation of Illinois N Drawing. Application September 9, 1947, f "Serial No. 773,078 I V in the boiler correlated with the Water level indicated in the conventional water glass attached to the boiler. -In other Words, there isno sharp line of demarcation between solid Water and foam in a boiler during rapid steam withdrawal.

The foaming of boiler water is actually arapid expansion of the water in a steam generating area of the boiler brought about by the fact that rapidly forming small steam-bubblesdo not coalesce, if at all, until a definite short time'after their formation. As a consequence, the entire volume of water in the generating area is ex panded by myriads 'of small bubbles until the thus formedso-called light water may fill the steam space and become entrained with jthe steam leaving the boiler. I 1 1 In other words, bubbles need not be particularly stable to cause boiler foaming. stabll: ity of the bubbles need only be such that the bub bles last but a very few seconds after passing the plane of the water levelindicated in'the water glass.

I have now found that the slight degree of stabilization of bubbles which suffices to cause foaming of boiler water may be largely or completely inhibited by the addition to the water of trilauroyl diethylene triamine, tetralauroyl triethylene tetramine, tetralauroyl tetraethylene pentamine, or pentacapryl tetraethylene pentamine. These are novel compounds not heretofore prepared.

.,5 .Qlaims. 1 (01. 252 -3211:] I v It is therefore animportant object of the pres- The foam inhibiting compositionsof the present invention may be introduced into steam boiler water in the form of colloidal dispersions that may be stabilized with tannin, gum-arabie, pectin, or the like. If desired, the foam inhibiting compositions may be introduced into the boiler in the form of a solution in an appropriate sol- V ven suchas-is propy1 dosages required are generally quite small, on the order of some few parts per million of boiler alcohol or the like. The

water. In general, from 0.1 to about 5 parts per million of. foam inhibiting compounds may be added to boiler Water, preferably in combination with tannin. Addition of foam inhibiting compounds maybe repeated as required to prevent foaming.

Trilauroyldiethylene triamine having the formula HN-oH2-oHkN oH; eH2-NH =o I =o =0 511B 2 111123 111112:

may be-preparedas follows. grams of lauric acid were heated with 12 grams diethylene triamine for 6 hours at to 200 C. Titration of the reaction mass with 1% normal alcoholic solution of sodium hydroxide, using Poirriers Blue as indicator, showed that the reaction mass contained 1.4% of unreacted acid. The product i soluble in benzene and ethyl acetate and contains 6.65% n g' n. a com ared w th th theoretical n on q nt n io' 46% l etra ro tr e hy en tr m na h i h fo m a:

may be. prepared as follows. 75 grams of lauric acid were heated with 17 grams triethylene tetramine at 180? to 220 C. for 6 hours. Titration of the reaction mass with normal alcoholic sodium hydroxide solution, using Poirriers Blue as indicator, showed that reaction mass contained 43 :unreacted acids. The product is soluble in benzene and ethyl acetate and contains 7.22% ni-. trogen, as compared with the theoretical nitrogen content of 6.73%.

V'Ietralauroyltetraethylene pentamine, having the formula:

( 3 0 C=O =0 H =0 11 2: $111123 uHn 11 23 may beprepared as follows. '75 grams lauric acid were heated with 22 grams tetraethylene pentamine at 180 to 200 C. for '6 hours. Titration of the reaction mass with normal alcoholic sodiflum hydroxide solution, using Poirriers Blue as indicator; showed that reaction mass contained 3.27% unreacted acid. The product is soluble in drous Na2SO4.

Tetralauroyl tetraethylene pentamine may also be prepared as follows. 80 grams of lauric'acid were heated with 19 grams of tetraethylene pentamine at. from 175 to' 185 C. for 21 hours, yielding a product having an acid number of 28.1.

The reaction mass obtained had a nitrogen con-.

tent of '7.12%. Correction for the acid content indicates a nitrogen content of 7.90%.

Pentacapryl tetraethylene pentamine, having the formula:

may be prepared as follows. v345 grams capric acid, 54 grams tetraethylene pentamine'and' grams of dry silica gel were heated together for hours at from l60 to 2109C. Titrati'onof the reaction mass with 6 normal alcoholic sodium hydroxide solution, using Poirriers Blue as indicatonshowed that 35.4% of the :acid had not reacted. The unreacted capric acid was removed by vacuum distillation, 124.2 grams being recovered. The residue from the distillation was recrystallized from 300 cc. hot acetone.= The in. soluble material which was filtered off .weighed 72.9 grams and formed a light brown powder melting at 107 to 110 C. and having a nitrogen content of 7.29%, compared with a theoretical nitrogen content of 7.3%.

Pentacapryl tetraethylene pentamine may also be preparedas follows. 1.1 lb. of tetraethylene pentaminewereplaced in a 4 liter beaker and heated with constant stirring over a free flame at 190 to 200 C. for hours. At this time, the free acidity had dropped to 5.56%. The product obtained had nitrogen content of 8.30% and, corrected for the unreacted acid, a nitrogen content 017.29%. Y

The'efliciency as foam inhibitor of the above identified compositions has been determined by testing in a laboratory boilerf operating un'de'r 200 lbs. per sq. in. pressure amfmmmimgem cc.' of a foaming water made -upb'y addinglto 1 liter distilled water /2 gram CaSOnZH'zO," 2 grams anhydrous NazCOs and 0.3 gram anhytions were added to the foaming water in 1 mg. portions. Trilauroyl diethylene triamine was found to inhibit foaming for 164 minutes; tetralauroyl triethylene tetramine; for 1'70 minutes;

tetralauroyl tetraethylene pentamine, for 124 procedure 5 lbs. of capric acid and The above identified composimay be varied through a wide range without departing from the principles of this invention and it is, therefore, not my purpose to limit the pat ent granted on this invention otherwise than necessitated by the scope of the appended claims.

;I claim as my invention:

' 1; The method of generating steam from a boiler water having a, tendency to foam on boiling which comprises dispersing into said water a material selected from the group consisting of trilauroyl diethylene triamine, tetralauroyl triethylene tetramine, tetralauroyl tetraethylene pentamine and pentacaproyl tetraethylene pentamine, and heating the resulting aqueous dispersionto the boiling point, said material being added in an amount sufficient substantially to inhibit the tendency of said water to foam on boiling.

-2. The method of generating steam from a boiler water having a tendency to foam on boiling which comprises dispersing into said water from 0.1 to parts per million of a material selected from the group consisting of trilauroyl diethylene triamine, tetralauroyl triethylene tetramine, tetralauroyl tetraethylene pentamine and pentacaproyl tetraethylene pentamine, said material. functioning to inhibit the tendency of said water to foam on boiling,

3. The method of generating steam from a boiler water having a tendency to form on boilingwhich comprises dispersing from 0.1 to 50 parts per million of pentacaproyl tetraethylene pentamine into said water, and heating the resulting aqueous dispersion to the boiling point, said pentacaproyl tetraethylene pentamine functioning, to inhibit the tendency of said water to foam on boiling.

4. The method of generating steam from a boiler water having a tendency to foam on boiling which comprises'dispersing from 0.1 to 50 parts per million of tetralauroyl tetraethylene pentamine into said water, and heating the resulting aqueous dispersion to the boiling point, said tetralauroyl tetraethylene pentamine functioning to inhibit the tendency of said water to foamon boiling.

5 The method of generating steam from a boiler water having a tendency to foam on boiling which comprises dispersing from 0.1 to 50 parts per million of tetralauroyl triethylene tetramine into saidwater, and heating the resulting aqueous dispersion to the boiling point, said tetralauroyl triethylene tetramine functioning to inhibit the tendency of said water to foam on boiling.

LEWIS O. GUNDERSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

1. THE METHOD OF GENERATING STEAM FROM A BOILER WATER HAVING A TENDENCY TO FOAM ON BOILING WHICH COMPRISES DISPERSING INTO SAID WATER A MATERIAL SELECTED FROM THE GROUP CONSISTING OF TRIAUROYL DIETHYLENE TRIAMINE, TETRAUROYL TRIETHYLENE TETRAMINE, TETRAUROYL TETRAETHYLENE PENTAMINE AND PENTACAPROYL TETRAETHYLENE PENTAMINE, AND HEATING THE RESULTING AQUEOUS DISPERSION TO THE BOILING POINT, SAID MATERIAL BEING ADDED IN AN AMOUNT SUFFICIENT SUBSTANTIALLY TO INHIBIT THE TENDENCY OF SAID WATER TO FOAM ON BOILING. 